Early aseptic loosening and inferior patient-reported outcomes of a cementless tibial baseplate in a modern total knee arthroplasty design.

Aims: This study reports the outcome of a modern total knee arthroplasty design using a cementless tibial baseplate compared to the full-cemented version.

Methods: Consecutive cohorts with 12-month follow-up were evaluated. Patients receiving a cementless tibial baseplate were compared to those who received a cemented tibial component. Endpoints included revision rates and reason for revision, patient-reported outcome measures (PROMs) using the Oxford Knee Score (OKS), and progressive radiolucency. Retrieval analysis was performed for the revised cases. Pearson correlation analysis and multiple regression analysis were used.

Results: A total of nine knees (7%) from the cementless cohort were revised, all due to aseptic loosened baseplate at a mean follow-up of 10.4 months (3 to 19), whereas the incidence of aseptic loosening of the cemented tibial baseplate was significantly lower at 0.5% (3/534; p < 0.001). The cemented cohort PROMs outperformed the cementless baseplate group at both 12 months' follow-up and the improvement from baseline (mean OKS 40.4 (SD 6.8) vs 38.5 (SD 8.1); p = 0.006; mean ΔOKS 18.8 (SD 9.0) vs 15.5 (SD 12.8); p < 0.001). There were no significant differences between the groups in the occurrence of new radiolucency at 12 months (p = 0.325). An elevated BMI was the only factor to correlate (r = -0.195) with worse values of ΔOKS (p = 0.048) in the cementless cohort. The multiple regression analysis determined that an increased BMI was the single independent predictor for aseptic loosening (p = 0.024) for the knees with a cementless tibial baseplate. Retrieval analysis suggested failed osseointegration.

Conclusion: In our cohort, there was a significantly higher incidence of aseptic loosening and worse PROMs at one year for the cementless tibial baseplate. An increased BMI may be an independent risk factor for aseptic loosening and inferior PROMs.