Cementless Cone Stem And Metal-On-Metal Articulating Surface For The Treatment Of Arthritis Following Congenital Hip Disease

OBJECTIVES. Cementless cone tapered stems reached a large success in Hip revision surgery, literally revolutioning the prognosis of many cases of dramatical bone stock loss. Nevertheless, little experience exists in the Literature about their use in primary arthroplasties. METHODS. The Cone Stem was designed in the 80's by Prof. Wagner. The stem is made of a rough blasted Titanium Alloy with a cone angle of 5 deg and 8 sharp longitudinal 'ribs'that cut into the inner cortex, providing excellent rotational stability. The ribs depth of penetration ranges between 0.1 and 0.5 mm and is also very important to achieve osteo-integration. The CCD angle is 135 deg . The stem is straight and can be implanted in any degree of ante- or retro-version thus being indicated in dysplastic arthritis where we need to correct anteversion. Between 1993 and 1998 the Senior Author (RB) has implanted 92 consecutive cone stems in 88 patients with dysplastic arthritis. The acetabular component was always cementless and in Titanium. The articulating surface was mostly Metal-on-Metal. The average follow-up was 10.1 years. According to the Hartofilakidis classification we had 63 patients of type A, 18 of type B and 11 of type C. RESULTS. Clinically we had 89% of Satisfactory results with no cases of anterior thigh pain.No patient required revision of the stem, while we revised a cup in Group C. Radiographically, 17% of patients showed some resorption in femoral zone 1 and 7. In 12 cases it was a narrow fissure due to the oscillations of proximal stem under load. This lesion was never progressive. In the same zones we observed 4 cases of real osteolysis. No radiolucent line was observed in other femoral zones. In the acetabular side we had 13 cases (14%) of radiolucency. CONCLUSIONS. Cone stem gave excellent clinico-radiographical results in dysplastic arthritis.