Abstract

The femoral stem "Contact", conceived in 1981, provides an excellent contact with metaphyseal-diaphyseal bone, on the medial and lateral cortices. The stress on the cement is not high; the cement fills the medulla in the anteroposterior direction. Five-year results in 92 prostheses were published at the annual meeting of the SO.F.C.O.T. in 1986. The follow-up after 10 years of 76 prostheses with a complete radiological evaluation showed neither loosening, nor space between cortex and prosthesis. The calcar remained unchanged after 5 years in 60 cases; in 11 patients the density was diminished and in 5 hips, a cavitation was seen. Around the top of the stem, 11 partial or total "wall-forming" deposits were seen. On 42 lateral x rays the bone cement interface was satisfactory. Cortical resorption, which was not seen before, is now apparent on the most recent controls. The cortical index (Hoffman), measured on 49 prostheses, was unchanged in 15 cases (30%). The narrowing of the cortex increases with age, being more frequent and significant and occurring earlier in women. This process was seen from the age of 65 years in females and about 75 in males. This natural increase in the size of the medulla induces a loosening of the stem. Loosening may be limited by the use of a snugly fitting cemented stem, with limited stress on the cement.