¹Presley T, ¹Granade M, ¹Eapen P, ²Smith L, ¹Yakkanti M, ¹Malkani A
¹University of Louisville, Louisville, KY, United States; ²UofL Health, Louisville, KY, United States

INTRODUCTION:
Alternative alignment concepts including kinematic (KA) and restricted kinematic (rKA) have been introduced to help improve clinical outcomes following TKA. There is a concern for implant survivorship using the concept of kinematic alignment due to deviation from neutral mechanical axis. Purpose of this study was to evaluate results of primary TKA using rKA concept with cementless implants given their potential for long-term biologic fixation.

METHODS:
This was an IRB approved retrospective study from a single institution of 200 consecutive primary, cementless TKAs using restricted kinematic alignment. 8 patients were lost to follow-up, leaving 192 (97.3%) with minimum 2-year follow-up. All procedures were performed using the same cementless implant design, anesthesia and postoperative protocols. Demographic data included age (mean 64.3 years), gender (93 males, 107 females), and BMI (mean 32.9 kg/m2). Outcome measures included Knee Society Scores (KSS), KOOS Jr., Forgotten Joint Score (FJS-12), overall satisfaction (5-point Likert scale), and complications. Statistics were performed using T-test.

RESULTS:
There was a significant improvement in KSS Function scores (52.1 to 87.5, p= < 0.001); KSS Knee scores (46.6 to 92.3, p= < 0.001); mean postop KOOS Jr. score was 86.0; Mean postop FJS-12 score was 74.4; and 92% patient satisfaction at 2 years. 6 (3%) patients underwent revision: instability (4), arthrofibrosis (1), traumatic arthrotomy (1), and there were no cases of PJI or aseptic loosening. Other complications included 16 (8%) manipulations for stiffness; 6 (3%) arthroscopy lysis for capsulitis; and 2 (1%) arthrotomy I&D.

CONCLUSIONS:
Results of primary TKA performed using restricted kinematic alignment along with the use of cementless implants appear promising and demonstrated excellent PROMs with 97% survivorship and no cases of failure due to aseptic loosening. Additional follow-up is needed to determine if rKA using cementless implants will be durable over the long term.