Does Cement Mantle Grading of Distal Femoral Replacements Correlate with Implant Survivorship?

Abstract

Distal femoral replacement (DFR) is increasingly being used as a salvage procedure for both oncologic and non-oncologic cases. However, as aseptic loosening after this complex surgery remains a concern, there is concomitant uncertainty in the role of cemented fixation in DFRs. The purpose of this study was to evaluate the outcomes following DFR according to femoral stem-to-construct ratio and cement mantle grading. This was a retrospective study from 2005 to 2022. The femoral stem-to-construct ratio was determined using radiographic measurements. Cement mantles were graded according to the Barrack grading system and were categorized into three groups: grade A, grade B, and grade C plus D. Clinical outcomes were subsequently compared between the groups. Of the 198 patients included for analysis, 130 (65.7%) were women, their mean age was 71 years (range, 25.0 to 95.9), and their mean body mass index was 32.1 (range, 17.0 to 63.0). In total, 48 cement mantles were categorized as grade A, 100 as grade B, and 50 as grade C plus D. The femoral stem-to-construct ratio was smaller in grade A than in grade B and grade C plus D (1.2 versus 1.5 versus 1.6, respectively, P < 0.001). There were 58 (29.3%) patients who had their DFR revised. The revision rate in grade A stems was 29.2%, compared to 25.0% in grade B stems and 38.0% in grade C plus D stems (P = 0.257). Loosening was observed in 4.2% of grade A stems, 5.0% of grade B stems, and 14.0% of grade C plus D stems (P = 0.118). This study demonstrated an association between a smaller femoral stem-to-construct ratio and better cement mantle grading. The loosening rate after DFR was comparable between all cement mantle gradings, with no increased risk of loosening with worse cement mantle grading.