Abstract
All-polyethylene (all-poly) tibial designs in primary total knee arthroplasty (TKA)
have been reconsidered with excellent clinical outcomes, survivorship, and cost-effectiveness.
However, whether all-poly tibial components provided comparable results to metal-backed
modular components during unicompartmental knee arthroplasty (UKA) remains unclear.
This study compared the clinical outcomes and prevalence of early failure between
all-poly and metal-backed modular components in UKA. We retrospectively reviewed the
records and radiographs of 101 consecutive UKAs. In total, 51 UKAs were performed
using all-poly tibial components; 50 others used metal-backed modular components.
Clinical and radiographic outcomes, adaptive bone remodeling assessed by radiographic
bone density, and early failure prevalence rates were compared. Despite a lack of
group differences in clinical and radiographic outcomes (p > 0.1 in all comparisons), adaptive bone remodeling at 2 years after surgery of all-poly
UKAs was more progressive compared with metal-backed UKAs (1.2 in all-poly UKA group
vs. 0.9 in metal-backed UKA group, p < 0.001). In addition, 6 of 51 all-poly UKAs failed within 2 years postoperatively,
whereas no metal-backed UKAs failed (11% in all-poly UKA group vs. 0% in metal-backed
UKA group, p = 0.027). All-poly tibial component use during UKA increased the risk of early failure,
which may be due to a failure in tibial loading distribution.
Keywords
all-polyethylene tibial components - metal-backed modular components - adaptive bone
remodeling - unicompartmental knee arthroplasty