Long-term radiographic follow-up of total hip replacements.

This report relates the long-term clinical result with the serial radiologic findings of 350 consecutive total hip replacements done by the author. Thirteen femoral components and one acetabular component have been revised, and 12 of the 14 components had shown radiologic changes in the surrounding cement prior to the need for revision. Available roentgenograms at 6 weeks, 1 year, 5 years, and 8 to 10 years after surgery made radiologic assessment possible in 129 hips. Heterotopic bone formation, calcar resorption and distal cortical hypertrophy all appeared to be primarily radiologic findings with little effect on clinical results. A variety of changes seen in the cement or bone-cement interface were noted on the femoral component side of 13.6% of the hips. None of these patients had any symptoms or functional limitations. These radiologic femoral cement mantle changes showed a high correlation with apparently inadequate initial cementing techniques and were usually already seen on the 1- and 5-year postoperative roentgenogram. Only one acetabular cup was identified as radiologically loose and one as migrated. Radiolucent lines at the bone-cement interface on the acetabular side showed vascillating increases and decreases on the serial roentgenograms. Since the lucent lines on the acetabular component side improved as often as they increased in size, these lucencies did not seem to be of similar predictive value as those on the femoral side. Of the hips followed 8 to 10 years only 2 circumferential and 10 lucencies greater than 2 mm could be found. I could not correlate these with inadequate cup position or inadequate cement mantle on the initial radiograph. The 29 patients in this series who were under 50 years of age did not have a revision rate or radiologic change different from the group as a whole.