Cementless versus hybrid fixation in primary total knee arthroplasty: a propensity score-matched analysis of mid-term outcomes

PURPOSE: Total knee arthroplasty (TKA) is an effective treatment for advanced gonarthrosis. This retrospective study compares cementless versus hybrid fixation in TKA, an under-investigated comparison in the literature, to describe mid-term clinical, radiographic, and perioperative outcomes between both fixation strategies. METHODS: We conducted a retrospective cohort study of 166 patients (age 50-70, adequate bone quality) undergoing primary cruciate-retaining TKA from November 2019 to May 2024. Fixation type was selected by the treating surgeons according to intraoperative assessment of tibial bone stock and press-fit stability. Patients were divided into two groups based on fixation: uncemented (cementless) vs. hybrid (cementless femoral, cemented tibial). Clinical (pain, function) and radiographic outcomes, perioperative complications, and surgical time were compared. Functional outcomes were assessed with Hospital for Special Surgery (HSS) and WOMAC scores; quality of life with the EQ-5D. A propensity score-matched analysis (1:1) was additionally performed to mitigate measured baseline confounding, matching on age, sex, body mass index (BMI), Charlson comorbidity index and preoperative HSS score. RESULTS: The mean follow-up was 36.8 ± 18.7 months. Uncemented fixation was associated with significantly shorter surgical time (65.2 ± 12.4 vs. 78.6 ± 15.1 min; p = 0.032), a modestly greater postoperative pain reduction on the VAS (7.25 ± 2.02 vs. 6.41 ± 1.94 points; p = 0.012), and a lower observed rate of late complications (1.2% vs. 10.8%; p = 0.028) compared to hybrid. The incidence of aseptic loosening was lower in the uncemented group (0.0% vs. 3.6%; p = 0.029), as was the presence of radiolucent lines (6.0% vs. 18.1%; p = 0.032). No significant differences were found in postoperative range of motion, HSS score improvements, WOMAC, or EQ-5D index between groups. The propensity-matched sub-analysis (n = 150) yielded directionally consistent findings, although these analyses reduce but do not eliminate residual confounding and remain underpowered for rare outcomes. CONCLUSION: Cementless TKA was associated with comparable mid-term functional outcomes to hybrid fixation, together with shorter operative time and lower observed rates of radiolucent lines and late complications. The difference in pain reduction was statistically significant but modest, and radiographic findings and rare events should be viewed as hypothesis-generating rather than as evidence of superior fixation performance or long-term implant durability. These findings suggest that cementless fixation may represent a reasonable alternative to hybrid fixation in appropriately selected patients, although longer-term prospective comparative studies are required to confirm implant survivorship and clarify the clinical relevance of these observations.