Abstract
I prefer monolithic, cylindrical, fully porous coated femoral components for most femoral revisions. Our institutional database holds information on 1000 femoral revisions using extensively porous-coated stems. To date, 27 stems have been rerevised (14 for loosening, 4 for infection, 7 for stem fracture, 2 at time of periprosthetic femoral fracture). Using femoral rerevision for any reason as an end point, the survivorship is 99 ± 0.8% (95% confidence interval) at 2 years, 97 ± 1.3% at 5 years, 95.6 ± 1.8% at 10 years, and 94.5 ± 2.2% at 15 years.
Similar to Moreland and Paprosky, we have identified prerevision bone stock as a factor affecting femoral fixation. Among the 777 femoral revisions graded for femoral bone loss, 59% of the femurs were graded as having no cortical damage before the revision, 29% had cortical damage extending no more than 10cm below the lesser trochanter, and 12% had cortical damage that extended more than 10cm below the lesser trochanter. When the cortical damage involved bone more than 10cm below the lesser trochanter, the survivorship, using femoral rerevision for any reason or definite radiographic loosening as an end point, was reduced significantly, as compared with femoral revisions with less cortical damage.
In addition to patients with Paprosky type 3B and 4 femoral defects there are rare patients with femoral canals smaller than 13.5mm or larger than 26mm that are not well suited to this technique. Eight and 10-inch stems 13.5 or smaller should be used with caution if there is no proximal bone support for fear of breaking. Patients with canals larger than 18mm may be better suited for a titanium tapered stem with flutes. While a monolithic stem is slightly more difficult for a surgeon to insert than a modular femoral stem there is little worry about taper junction failure.
