# Cementless vs. Cemented Total Knee Arthroplasty: Reduced Operative Time with Comparable Perioperative Safety—A Retrospective Cohort from a Tertiary Care Center

## TL;DR

Cementless knee replacements take less time to perform than cemented ones without increasing blood loss or complications, based on a study of patient data.

## Contribution

The study demonstrates that cementless TKA reduces operative time without compromising safety, offering a practical advantage in surgical settings.

## Key findings

- Cementless TKA had a significantly shorter operative time compared to cemented TKA.
- There were no clinically relevant differences in hemoglobin decline or anemia-related complications between the two groups.

## Abstract

Background: Total knee arthroplasty (TKA) is a widely performed and highly successful procedure, with cemented fixation historically considered the standard. Advances in implant design have renewed interest in cementless fixation, which shows comparable survivorship and increasing use, particularly in younger patients. Evidence on perioperative outcomes remains mixed, prompting this study to compare hemoglobin decline and operative time between cemented and cementless TKA of the same design. Methods: This monocentric retrospective cohort study included consecutive patients undergoing primary TKA between 2019 and 2021, divided into cemented and cementless groups. Inclusion criteria were primary osteoarthritis, age > 45 years, hemoglobin > 13 g/dL, ferritin > 100 ng/mL, and complete perioperative hemoglobin data (preoperative, PostOperativeDay (POD)1, 3, 5). Primary outcomes were operative time and hemoglobin trajectory, analyzed using multivariable regression and mixed-effects models adjusted for age, sex, and implant design. Propensity score matching was performed as a sensitivity analysis. Results: A total of 123 TKAs were analyzed (63 cementless, 60 cemented). Cementless TKA had a shorter operative time than cemented (72.0 ± 12.0 vs. 79.8 ± 15.1 min; 95% CI −12.2 to −2.8; p < 0.01). Cementless fixation was associated with significantly shorter operative time (72.0 ± 11.8 vs. 79.8 ± 15.1 min, p < 0.01), a difference that remained significant after multivariable adjustment and propensity score matching. Postoperative hemoglobin declined in both groups, with no significant unadjusted between-group differences at any timepoint. In adjusted mixed-effects models, cementless TKA was associated with a slightly greater hemoglobin decline compared with cemented TKA, with mean adjusted differences of −0.56 g/dL on POD1 (95% CI [−0.95, −0.17]), −0.53 g/dL on POD3 (95% CI [−0.91, −0.14]), and −0.34 g/dL on POD5 (95% CI [−0.64, −0.04]). However, this was not clinically relevant, as no transfusions or anemia-related complications occurred. Conclusions: Cementless TKA was associated with reduced operative time compared with cemented fixation, an effect robust to adjustment and propensity score matching. These conclusions apply to a selected, relatively non-anemic cohort. Although hemoglobin decline was slightly greater with cementless fixation, the difference was small and not clinically meaningful.