Radiographic assessment of cementless femoral components. Correlation with intraoperative mechanical stability.

The correlation between preoperative radiographic findings and intraoperative testing for stability was evaluated for 75 cementless femoral components. Fourteen of 45 porous-coated prostheses were unstable. The following radiographic signs were correlated with instability in order of significance: radiolucent lines at the bone-prosthesis interface covering greater than 50% of the porous interface, a distal pedestal, calcar hypertrophy, poor implant-cortical contact, and varus component alignment. Signs consistent with implant stability were good implant-cortical contact, spot welds, and calcar atrophy. Preoperative radiographs have predictive value in assessing the mechanical stability of the cementless femoral component at the time of surgery.