Outcomes of a newer-generation cementless total knee arthroplasty design in patients less than 50 years of age.

Background: Younger patients undergoing cemented total knee arthroplasty (TKA) may be at risk for lower implant survivorship and higher revision rates due to the historical increased prevalence of aseptic loosening and instability in this cohort. The recent advances of cementless TKAs may mitigate some of these complications. However, there is a paucity of studies reporting on patients who are under 50 years who have undergone a cementless TKA. Therefore, this study evaluated: (I) implant survivorship; (II) functional outcomes and complications; and (III) radiographic outcomes in patients who were less than 50 years of age and underwent cementless TKA.

Methods: A total of 29 patients (31 knees) younger than 50 years who underwent primary TKA at a single institution (Mount Sinai Beth Israel, New York, New York, USA) from June 2008 to May 2014 were included. Their mean follow-up was 4 years (range, 2 to 6 years). The cohort included 20 women and 9 men who had a mean age of 45 years (range, 34 to 49 years), and a mean body mass index (BMI) of 33 kg/m2 (range, 22 to 54 kg/m2 ). The preoperative knee diagnoses were osteoarthritis (n=24), osteonecrosis (n=5), and rheumatoid arthritis (n=2). A Kaplan-Meier analysis was used to calculate the all cause implant survivorship. Functional outcomes and all complications were recorded for each patient. Additionally, radiographic evaluation using the new Knee Society Radiographic Evaluation and Scoring System was performed.

Results: The overall implant survivorship was 100%; there were no failures or revision surgeries performed as of the latest follow-up visit. At the latest follow-up, the mean Knee Society pain score was 92 points (range, 80 to 95 points) and the mean Knee Society function score was 84 points (range, 70 to 90 points). Additionally, the mean knee extension was 1 degree (range, 0 to 5 degrees) and the mean knee flexion was 125 degrees (range, 95 to 140 degrees). Furthermore, at the latest follow-up, on radiographic evaluation, there was no evidence of component loosening, subsidence, radiolucency, gap formation, or reactive changes, and there were no postoperative complications.

Conclusions: Cementless fixation of TKAs had excellent survivorship and functional and radiographic outcomes at midterm follow-up in patients younger than 50 years. Although longer follow-up is needed, these cementless TKA implants appear to provide promising results in younger patient populations.