Cementless versus cemented fixation in image-based robotic total knee arthroplasty guided by functional knee positioning principles

Abstract

Introduction: Under functional knee positioning (FKPos) principles, residual varus or valgus alignment of the tibia and femur may be maintained, resulting in loading conditions that differ from those observed with mechanical alignment. Consequently, there is a need for evidence regarding implant fixation (cemented or cementless) in this context. This study aimed to evaluate the impact of implant fixation type (cemented versus cementless) on clinical outcomes, complications, and implant survival in robotic-assisted total knee arthroplasty (TKA) guided by FKPos principles.

Methods: A retrospective comparative analysis of 393 patients who underwent robotic-assisted primary TKA was performed. Patients were divided into two groups: cemented (n = 85) and cementless (n =276) fixation. Radiographic alignment, functional outcomes using the Knee Society Score (KSS) and Forgotten Joint Score (FJS), complication rates, and implant survival were assessed at a minimum 2-year follow-up. Subgroup analyses based on femoral and tibial fixation types were also conducted.

Results: Both fixation methods achieved comparable functional outcomes (KSS and FJS) and implant survivorship, with no significant differences in revision rates. Hematomas were significantly more frequent in the cementless group (12.32% vs. 8.24%, p = 0.02). Subgroup analyses of femoral and tibial implants showed no significant differences in functional outcomes.

Discussion: This study is the first to assess the influence of fixation type on outcomes in robotic-assisted TKA performed under FKPos principles. Both cemented and cementless fixation methods are safe and effective.

Keywords: Cemented; Cementless; Functional alignment; Press fit; Total knee.

Figure 1

Kaplan-Meyer survival analysis of the two groups, taking into account both infection-related and aseptic causes of revisions. Polyethylene exchange as part of the debridement, antibiotics, and implant retention procedure has been included as implant failure in this analysis. Kaplan Meier survival analysis showed that group B (cemented implants) did not have significantly higher risk of all-cause revision (infections and aseptic loosening) compared to group A (cementless implants) (p = 0.57).