CLINICAL AND RADIOGRAPHIC SHORT MID-TERM OUTCOMES OF PRIMARY TOTAL STABILIZER KNEE ARTHROPLASTY

Abstract

A successful Total Knee Arthroplasty (TKA) requires stability, but rarely in primary TKA, a prosthesiswith more constraint than a posterior-stabilizer (PS) is necessary. In patients with severe varus/valgusdeformities with incompetent collateral ligaments or in knees that cannot be adequately balanced afterligaments release, a total-stabilizer (TS) prosthesis may be required. The purpose of our retrospectivestudy is to evaluate clinical and radiographic outcomes at short mid-term follow-up in patients treatedwith a TS TKA. Between January 2013 and August 2016, 36 patients (38 knees) were treated with StrykerTriathlon TS cemented implants. Clinical and radiographic evaluation were performed preoperativelyand postoperatively at 1 month, 3 months, 6 months, 1 year and at 1-year intervals thereafter. At finalfollow-up, 33 patients (35 knees) remained and were included in this study and followed with a meanfollow-up of 26.6 months. Clinical evaluation was performed using the Western Ontario and McMasterUniversities Arthritis Index (WOMAC score) and the Knee Society rating system that is subdivided intoa knee score (KS) that rates only the knee joint itself and a functional score (FS). Knee Score (KS) andFunctional Score (FS) increased significantly from a mean pre-operative value of 48 and 45, respectively,to a post-operative value at last follow-up of 86 and 82, respectively. Also WOMAC score improvedsignificantly: the mean pre-operative WOMAC score was 45, while the mean post-operative WOMACscore, at last follow-up, was 19. The difference between pre- and post- operative results was significantat statistical analysis. In our opinion, when the adequately prosthesis balancing isn’t possible, because ofprimary or secondary severe varus/valgus deformity or severe soft tissues retraction, an available optionis to perform a total knee arthroplasty with a total stabilizer polyethylene insert. TS prosthesis gives morestability during the most of ROM and, in addition, Triathlon system provides surgeons the possibility tochoose a more constrained implant, than a standard PS one, during surgical procedure saving the bonestock. Our experience with this kind of prosthesis has provided good clinical and radiographic outcomesat a short mid-term follow-up with a low-rate of complications.