Abstract
PURPOSE: To evaluate how changing the native posterior tibial slope (PTS) through implantation of a cemented medial unicompartmental knee arthroplasty (UKA) impacts clinical and radiographic outcomes, specifically whether it correlates with the occurrence of tibial periprosthetic radiolucency or tibial aseptic loosening (AL). METHODS: This retrospective study analyzed 63 patients with cemented medial UKAs with a minimum follow-up of five years. Patient-reported outcomes (PROMs) included the Oxford Knee Score (OKS). Radiographic parameters assessed were: PTS, mechanical axis, prosthetic joint space height, tibial component obliquity, intraprosthetic divergence, and tibial periprosthetic radiolucency. Partial Pearson correlation and multiple linear regression analyses were used to evaluate the relationship between tibial periprosthetic radiolucency and demographic or radiographic parameters. RESULTS: Of 63 patients (mean age 68.9 ± 7.9 years, follow-up 62.5 ± 8.8 months), 5 knees (7.9%) demonstrated tibial periprosthetic radiolucency ≥ 2 mm. The mean postoperative PTS change was 3.8 ± 2.6°, mechanical axis change: 2.5 ± 1.8°, prosthetic joint space height: 9.2 ± 3.1 mm, tibial component obliquity: 2.5° ± 3°, and intraprosthetic divergence angle: 5° ± 4°. OKS averaged 43.9 (range 22-48), with a mean knee flexion of 123.4 ± 6.8°. Statistical analysis showed no significant associations between tibial periprosthetic radiolucency and demographics, radiographic parameters, or PROMs. Changes in PTS did not correlate with a range of motion (ROM), PROMs, or radiolucency. CONCLUSION: In our cohort, the deviation from native PTS following implantation of the cemented tibial component did not show a significant correlation with tibial periprosthetic radiolucency, PROMs, or ROM at mid-term follow-up.