One key question for orthopaedic surgeons regarding revision total knee arthroplasty (TKA) is how best to affix femoral and tibial stems. The August 17, 2016 edition of the Journal of Bone & Joint Surgery contains findings from a Level I randomized trial by Heesterbeek et al . that addresses this clinical conundrum.
Thirty-two patients with Type-I or II bone defects who needed a revision TKA received the same basic implant, with the femoral components and tibial baseplates being cemented in all cases. However, in half the patients the femoral and tibial stems were cemented, and in the other half the stems were press-fit (so-called hybrid fixation).
Measuring micromotion with radiostereometric analysis (RSA) at baseline, 6 weeks, and 3, 6, 12, and 24 months, the authors found no significant between-group differences in component migration. Similarly, at the 2-year follow-up, there were no significant between-group differences in clinical scores, including KOOS and visual analog ratings of pain and satisfaction.
The authors expressed concern about what they deemed the “relatively high” number of components in both groups that migrated > 1 mm (translation) or > 1° (rotation), and they are continuing to follow all these patients to determine whether clinically relevant component loosening eventually ensues.