Short-term functional recovery and inflammatory response following cruciate-retaining versus posterior-stabilized total knee arthroplasty in patients with varus knee osteoarthritis: a retrospective cohort study

In this study, we sought to investigate the effects of posterior cruciate ligament (PCL) retention during total knee arthroplasty (TKA) on short-term functional recovery and inflammatory responses in patients with varus knee osteoarthritis to guide prosthesis selection for this population. This single-center retrospective cohort study evaluated 75 patients with varus knee osteoarthritis who underwent TKA between February 2020 and January 2024. They were categorized into the posterior-stabilized (PS) group ( n = 36) and the cruciate-retaining (CR) group ( n = 39) based on the prosthesis implanted. Prosthesis selection was non-randomized and determined by the attending surgeon based on PCL integrity, the degree of varus deformity, and intraoperative soft-tissue balance. Inflammatory markers were assessed through postoperative day 7, while pain, range of motion (ROM), and functional outcomes were evaluated up to 3 months postoperatively. A mixed-design analysis of variance evaluated the effects of group, time, and group × time interactions on Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores. The primary outcome was the change in WOMAC scores from baseline to 3 months postoperatively. Postoperative Visual Analog Scale (VAS) scores decreased, whereas ROM, WOMAC, Lysholm, and Hospital for Special Surgery (HSS) scores improved from baseline in both groups. A significant group × time interaction effect was observed for WOMAC scores [F(1, 73) = 8.412, P = 0.005, partial η² = 0.103]. The difference in change between the CR and PS groups was − 4.74 points (95% confidence interval [CI]: −8.00 to − 1.48). Significant group × time interaction effects were observed for interleukin (IL)-1β, IL-6, and tumor necrosis factor α levels. The differences in changes between the CR and PS groups were − 8.17 pg/mL (95% CI: −12.78 to − 3.56), − 8.64 pg/mL (95% CI: −13.82 to − 3.46), and − 55.05 pg/mL (95% CI: −85.17 to − 24.93), respectively. The group × time interaction effects for VAS scores, ROM, Lysholm scores, and HSS scores were not statistically significant. No statistically significant difference was observed in the incidence of complications between the two groups; however, the small number of complication events precluded a definitive assessment of whether the two prostheses had comparable safety profiles. In this retrospective cohort study, CR prosthesis use was associated with lower 3-month WOMAC scores and attenuated reduced inflammatory marker levels at postoperative day 7. However, no significant differences were observed between the CR and PS groups in the magnitude of improvement in VAS, ROM, Lysholm, or HSS scores. Due to the short follow-up period, long-term functional outcomes, prosthesis survivorship, revision risk, instability, or prosthesis wear could not be assessed. Therefore, the results should be interpreted as short-term exploratory findings and do not establish the superiority of CR prostheses over PS prostheses.