The Libra® stems are straight femoral prostheses, either cementless and coated with hydroxyapatite or cemented with a highly polished surface. SERF has developed this femoral prosthesis from a well known and proven concept of conical shape and quadrangular section. However SERF has undertaken some modifications to the proximal area with a view to enhancing the primary and secondary fixation. A progressive increase in neck length to fit the needs of a large population.