Purpose: Polyethylene particles produced from metal-backed tibial (MBT) implants are understood to contribute to bone loss and component loosening. This, along with advanced surgical techniques, improved materials and increasing costs, has renewed interest in all-polyethylene tibias (APTs). We investigated peri-APT bone mineral density (BMD) in patients, expecting to find no differences between two post-operative values.
Methods: Patients over 65 years, with BMI ≤ 37.5 kg/m2 and no previous joint replacements were recruited to have computer-navigated total knee arthroplasty using an APT. The study cohort (n = 27) had mean age of 71.9 (SD 4.35) and BMI of 31.2 (SD 3.8). The BMD examinations were performed 6 weeks and 18 months post-operatively. Six regions of interest (ROI) were identified on anterior/posterior and lateral dual-energy X-ray absorptiometry scans. For each ROI, BMD relative differences (RDs) were determined between limbs and RDs at the two time points were compared.
Results: No differences were found between the RDs for any ROI. No revisions or complications were reported. At 18 months post-operatively, 79.2% of the cohort were very satisfied or satisfied with the outcome of their surgery and Oxford Knee Scores improved significantly compared to pre-operatively (p < 0.001). Mean knee range of motion was 102° (SD 10.7°), and mean leg alignment was 2.0° valgus (1-6°valgus).
Conclusion: Results from BMD analysis suggest that implants were well fixated without compromising function. We believe that using APTs with computer navigation is a viable cheaper option to MBTs for patients who are less active, have lower BMI and good bone quality.
Keywords: All-Polyethylene Tibia; Bone Mineral Density; Functionally Impaired Elderly; Total Knee Arthroplasty.
© 2023. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.