A low patella is frequently a complication of a lesion of the knee but it can also present secondary symptoms of its own. The authors describe an original method for assessment of the vertical level of the patella. They have tried to establish a relationship between the low situation of the patella and pain of a certain type associated with limited flexion of the knee. Physiopathological and biomechanical evidence is taken into account. In most instances, a low patella is secondary either to a mechanical cause, natural or iatrogenic, or to an inflammatory cause such as algodystrophia. 29 patients out of 128 observed cases have been operated on. 17 of these were due to excessive transplantation of the anterior tibial tubercle. In most of the cases the tibial tubercle was transplanted upwards in association with a joint release. In only 3 cases a patellectomy was done. The results were excellent or good in half of the cases and unsatisfactory in the other half.