Low frequency of radiolucent lines in 3D-printed porous-coated tibial cementless baseplate at 1-year follow-up.

Purpose: A recently introduced 3D-printed porous-coated tibial baseplate (ATTUNE AFFIXIUM, DePuy Synthes) was hypothesised to yield radiographical and clinical results that are comparable to those of its cementless predecessor with sintered beaded porous coating (POROCOAT, DePuy Synthes).

Methods: A consecutive series of total knee arthroplasties (TKAs) was performed by a single surgeon using a baseplate covered with either AFFIXIUM® 3D-printed porous coating or POROCOAT® sintered beaded porous coating. The presence of radiolucent lines (RLLs) and bone on-growth over the surface of the tibial baseplate were retrospectively reviewed at 1 week, 1, 2, 4, 6 months and 1 year postoperatively. The 2011 Knee Society Score, Forgotten Joint Score-12 (FJS-12), hip-knee-ankle (HKA) angle were also reviewed. One-to-one matching was performed for age, sex, body mass index and preoperative University of California, Los Angeles score. Fisher's exact test or independent Student's -test was used for statistical analyses.

Results: Fifty AFFIXUM® and 50 POROCOAT® cementless TKAs were reviewed after 1:1 matching at 1 year postoperatively. RLLs appeared in 15 knees (30%) of POROCOAT® TKAs at 6 months postoperatively, whereas RLLs appeared in two knees (4%) of AFFIXIUM® TKAs (<0.01). RLLs in 6 of 15 POROCOAT TKAs (40%) and 1 of 2 AFFIXIUM TKAs (50%) disappeared 1 year postoperatively. Bone on-growth over the surface of the tibial baseplate was observed in the same way in both groups. There were no significant differences in the 2011 Knee Society Scores and Forgotten Joint Scores-12 between the cohorts, with no patients requiring revision surgery (not significant).

Conclusion: A very low frequency of RLLs was observed on a newer 3D-printed porous-coated tibial baseplate design for TKA at 1-year follow-up.

Level Of Evidence: Level III, retrospective cohort study.