Are cementless stems more durable than cemented stems in two-stage revisions of infected total knee arthroplasties?
The routine use of stems in revision TKA improves survival rates by enhancing the stability of the prosthesis. The ideal method of stem fixation (cemented or uncemented) in two-stage reimplantation remains controversial.
The purpose of this study was to answer the following questions: (1) Are rerevision rates for aseptic loosening comparable between cemented stems and uncemented stems in two-stage reimplantation? (2) Is the reinfection rate comparable between antibiotic-impregnated cemented stems and uncemented stems for two-stage reimplantation? (3) Are there any differences in Knee Society radiographic scores between stem techniques?
A retrospective analysis was performed in all patients who underwent two-stage reimplantation between 1990 and 2010 at Anderson Orthopaedic Research Institute (AORI) and OrthoCarolina (OC). One hundred fourteen patients with 228 stems met the inclusion criteria. Of these 228 stems, 102 stems were cemented and 126 stems were uncemented. The indication for stem fixation was largely institution specific; AORI used cementless stems 92% (118) of the time, whereas OC used a cemented stem 92% (92) of the time. A 2-year minimum radiographic and clinical followup was required for inclusion into the study. Radiographic evaluations were performed using a modification of the Knee Society radiographic score.
Rerevision rates for aseptic loosening were comparable with three cemented and three cementless stem constructs. The reinfection rate was also comparable between cemented and cementless stems (p = 0.86). Using post hoc analysis, 32% of cemented stems were radiographically classified as loose or closely observe (33 of 102) compared with 17% of the cementless stem group (21 of 126; p = 0.006). Patients with good bone quality had a significantly lower rate of radiographic loosening compared with patients with poor bone quality (p = 0.01). There was no significant correlation with radiographic loosening and level of constraint (p = 0.90) or use of articulating versus static antibiotic spacer (p = 0.06).
In this retrospective study, cementless diaphyseal-engaging stems had a lower rate of radiographic failure than did cemented stems in two-stage reimplantation. Reinfection rates remain similar despite the absence of antibiotic cement in the cementless constructs. At this time we believe the use of hybrid, cementless diaphyseal-engaging stems should be considered as a possible option at the time of reimplantation.
Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.