[Does the type of prosthesis have an effect on the development of periarticular ossification?]

We checked up the hip operations that were done by the same surgeon in the years 1974-76 and 1984-86. For this examination we had 115 Müller Charnley prosthesis and 75 anatomically straight stems type SF. The heterotopic ossifications were classified according to Arcq. The aim was to find out if the form and type of the femoral stem, the changing of the leg length and of the CCD-angle, the post operative CCD-angle and the number of blood transfusion influences the dimension of heterotopic ossifications. The groups with higher amount of periarticular ossification (Arcq grade 2 and 3) are generally smaller. In the case of SF prostheses the ossifications raised when the CCD angle difference also raised. But the Müller/Charnley prostheses showed quite the contrary. Though there was no significance in this manner. Although in the other controlled factors there were no significant differences. The difference that was found between the two types of prosthesis was equalized with another factor: Low-dose heparin. This was the only significant influence on heterotopic ossification.