[Chronic instability of the knee].

During the last few years, major advances have been achieved in our understanding and treatment of chronic instability of the knee joint. The central hub (ACL and PCL) is the most important stabilizing element, and its rupture usually results in slipping knee, pain and recurrent hydrarthrosis, which are particularly frequent and severe in athletes. However, in some circumstances the loss of the anterior cruciate ligament can be compensated for by other stabilizing elements or by an excellent musculature. In patients with slipping knee, clinical, radiological and even arthroscopic examinations are necessary to decide on the treatment to be applied. This treatment depends on the importance and type of laxity, on the presence or absence of meniscal and cartilaginous lesions, on the degree of functional impairment and on the patient's life style. Several methods can be used, from rehabilitation alone to the replacement of the deficient ligament(s) by autografts or artificial ligaments. Treatment should not be stereotyped, and only specialist can determine the best method for each individual patient.