Reply to the Letter to the Editor: No Difference Between Trabecular Metal Cones and Femoral Head Allografts in Revision TKA: Minimum 5-year Followup.

To the Editor,

I would like to thank Chen and colleagues for their interest in our work, and for continuing the discussion on this topic.

The authors are correct in noting that of the 45 TKA revisions, surgeons used femoral head allograft for 30 TKA revisions (66.7%, not 75%) and that surgeons used trabecular metal cones for 15 TKA revisions (33.3%, not 25%).

Additionally, in the Trabecular Metal Cone Technique section, the authors found a discrepancy between the data presented in the text and Table 1. The data presented in the text is correct—four Type 2B and two Type 3 femoral defects and two Type 2A and seven Type 2B tibial defects were treated using trabecular metal cones. We have created an erratum to correct these errors.

Regarding the conclusions drawn from this study, readers should consider the second paragraph in the Discussion section, where we mention the small number of patients in our study group. We also stated in the Methods section that, at our institution, trabecular metal cones became the “preferred technique as a result of their relative ease of use” [1]. We used these cones when we encountered Anderson Orthopaedic Research Institute Type 3 defects, however, we do not believe that our conclusions should be overstated since we only used the cones on two patients with Type 3 defects. In our study, the use of both femoral head allograft and trabecular metal cones are associated with encouraging results and low rates of complications. Allografts can be used in this situation with encouraging results [2].

Regarding radiostereometric analysis (RSA), we agree that RSA is an accurate method for assessment of migration patterns of the cones, but this was not the focus of our study. Our goal was to compare the results of femoral head allograft and trabecular metal cones in revisions TKA. The radiographs in our study were performed in our center using standardized techniques and reviewed by at least two independent orthopaedic surgeons to minimize interpretation errors.