Mean Three-Year Survivorship of a New Bicruciate-Retaining Total Knee Arthroplasty: Are Revisions Still Higher Than Expected?

ABSTRACT

BACKGROUND: Given the need for continued post-market surveillance, especially on novel implants, the present study attempts to determine the 3-year survivorship and patient-reported outcomes of a contemporary bicruciate-retaining total knee arthroplasty design, and to determine if a learning curve existed which could explain previously reported revision rates. METHODS: We performed a retrospective review on a consecutive series of 141 bicruciate-retaining total knee arthroplasties performed at our institution between May 2013 and October 2015. Thirty-four knees (19%) missing 2-year follow-up were excluded. Mean follow-up was 3 years (range 0.34-4.9). Patients who died (n = 5) or were revised prior to 2 years (n = 6) were included. A Kaplan-Meier analysis was used to evaluate revision-free survival. RESULTS: Survivorship at 3 years was 88% (82%-93%). Revisions were for isolated tibial loosening (5/19), anterior cruciate ligament (ACL) impingement (3/19), pain (4/19), unknown reasons (3/19), femoral and tibial loosening (2/19), ACL deficiency (1/19), and arthrofibrosis (1/19). The mean physical function computerized adaptive test T-score was 45 units (range 23-63). The mean T-scores for Patient-Reported Outcomes Measurement Information System Global measures were 49 (range 27-68) for physical health, 50 (range 28-68) for mental health, and a median 3 (interquartile range 1-8) on the numeric pain scale. CONCLUSION: Revision-free survival of 88% at 3 years was lower than existing traditional TKA designs. The primary failure mechanisms were tibial loosening, ACL impingement, and pain. In the setting of higher than anticipated revision rates, despite patient-reported outcomes that are not different than seen in the general population, it is possible that further refinement in implant design or surgical technique may be needed prior to widespread use of this, or similar implant designs.