Cementless Total Ankle Replacement

Abstract

Category: Ankle Arthritis Introduction/Purpose: Total ankle replacement (TAR) was initially performed with first-generation cemented components. These constructs showed unacceptable revision and complication rates, in part due to the difficulty of obtaining a uniform cement mantle and the unique difficulties with TAR regarding the inability to dislocate the joint for exposure. Early concerns with polymethylmethacrylate (PMMA) in knees led to multiple studies evaluating fixation of total knee components by bone ingrowth using prospective randomized studies, registry data, and radiostereographic analysis. These studies have shown that if micromotion can be kept below 150 micrometers, cementless fixation could be anticipated. Similar benefits were anticipated with TAR, however the literature supporting cementless TAR by contrast appeared sparse. A systematic literature review was conducted to evaluate the literature supporting cementless TAR. Methods: A systematic review of the English language literature regarding cementless fixation in TAR was performed. Pubmed, Embase, Web of Science, and Google Scholar were searched using the terms “total ankle arthroplasty,” “total ankle replacement,” “cement,” “porous ingrowth”, “biologic fixation”, and “cementless” from the inceptions of these search engines until June 2017. To ensure that no relevant studies were missed, the reference sections of all studies selected for final analysis were additionally reviewed. All potentially relevant papers were compiled to determine whether they fit the previously established inclusion criteria. Exclusion criteria included non-English language studies, non-human or laboratory studies, and isolated case reports. The results of this literature review were analyzed using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). Results: The available literature was limited to five articles. Kofoed et al. reported TAR using the STAR ankle, and stated that there was no difference. Brigido et al. using digital radiography of the uncemented INBONE implant, showed that migration was only 0.7 mm at one year and 1.0 mm at two years. Fong et al. performed a preliminary study evaluating the possibility of stereo metric analysis of micromotion, but validated the possibility only. Fevang et al. in a registry review noted that: “The failures in early studies usually occurred with cemented implants. In general, uncemented prostheses have been associated with better results than cemented ones.” Takakura et al. noted a 27% success rate with a cemented ceramic TAR versus a 67% success rate without cement Conclusion: In contrast to the robust literature regarding cementless knee and hip arthroplasty, the literature justifying cementless TAR is surprisingly limited. This lack of literature has had significant impact on the performance of TAR in the US, as virtually all TARs are put in “off-label” without cement with additional liability risks imposed by the use of medical devices in this fashion. While prospective randomized studies comparing cemented to cementless third-generation TARs may violate clinical equipoise, other techniques such as stereometric sequential radiographs, comparative registry outcome data, and systematic retrieval data would allow validation of cementless TAR as a viable technique.