Early Femoral Loosening of the Titanium 3M Capital Cemented Hip: A Lesson Relearned

A 4-year follow-up study is presented comparing 3M Capital cemented hip replacements with Charnley low friction arthroplasty controls. The mean radiological follow-up in the Capital and Charnley groups was 47 months (25 to 61) and 47 months (23 to 66) respectively. All cases were performed by the same surgical team over the same period (April 1991-October 1993). The operative technique including femoral preparation and cementing technique was identical in each group. Charnley broaches were used for femoral preparation in both groups and Charnley cups were used in all cases. In all of the 3M Capital cases cobalt-chrome femoral heads were used. There was no case selection for either group. Six of the 21 Capital femoral components were deemed to be loose on radiological criteria. None of the Charnley hips was loose. This represents an unacceptably high incidence of radiological femoral stem loosening in the Capital hip replacement. A previous uncontrolled study has attributed early failures to deficient femoral preparation and/or cementing technique. We suggest that early femoral stem loosening in the Capital hip occurs despite satisfactory operative technique in contrast with the results using the Charnley total hip replacement.