Early experience with a new total knee implant: maximizing range of motion and function with gender-specific sizing

Patients considering total knee arthroplasty (TKA) now have higher expectations of performance including long-term implant survival and a rapid return of normal function. While modern implant systems have many sizes available, implant fit - especially in women - is often imperfect. The ability to achieve outstanding outcomes has many factors, requiring excellent implant fit, alignment, stability, range of motion, and kinematics, as well as long-lasting bearing surfaces and durable fixation. We present the initial two years of experience of 668 consecutive cemented total knee arthroplasties using an implant and bearing surface specifically designed to address these issues. The Triathlon TKA uses anthropomorphic sizing, taking into account the gender-specific variable aspect ratio for a better fit. Modified posterior femoral condylar geometry coupled with a rotary arc polyethylene design allows for flexion greater than 150 degrees while rotating 20 degrees internally and externally both in flexion and extension. The X3 polyethylene insert has demonstrated superior wear characteristics. Early outcomes revealed mean Knee Society pain and function scores, improving from a preoperative total score of 78 to a postoperative score of 182. Patients exhibited a rapid return of knee motion from a mean preoperative flexion of 102 degrees to 116 degrees at 6 weeks, 124 degrees at 3 months, and 128 degrees at 1 year. Whereas long-term results cannot be predicted, no early failures or serious complications were encountered. A prospective long-term outcome study of this cohort is underway.