Purpose: Bi-cruciate-retaining total knee arthroplasty (BCR-TKA) is recognized as an alternative to the cruciate-retaining total knee arthroplasty (CR-TKA) within the pursuit of retrieving the "forgotten artificial knee joint". The aim of this study was to provide a short-term comparison in functional and clinical outcomes between BCR- and CR-TKA.
Methods: The cohort consisted of 61 BCR-TKA patients, matched with 61 suitable CR-TKA patients, and operated between 2014 and 2016 due to osteoarthritis. Patient-reported outcome measurements were assessed preoperatively and at 3, 12, 24 and 36 months postoperatively. In addition, perioperative conditions were observed and radiological images were analysed pre- and 1 year postoperatively. Effect size for the FJS-12 was calculated at 3-year follow-up to quantify the difference between BCR- and CR-TKA.
Results: Patients reported a significant improved health-related quality of life (p = 0.017) and a non-significant difference in joint awareness at 3-year-follow-up with a moderate effect size (0.4). Operating time in BCR-TKA (1:16, ± 0:16) is significantly longer (p < 0.000) than in CR-TKA (0:50, ± 0:12). Blood loss significantly increased (p = 0.005) in BCR-TKA (246.4 cc, 79.8) compared to CR-TKA (195.5 cc, ± 106.2). Comparable length of hospital stay (n.s.) was observed in BCR-TKA (1.1 days, ± 1.1) and CR-TKA (1.3 days, ± 1.3). Outliers of the hip-knee-ankle axis occurred significantly more frequent (P = 0.015) in the BCR group (37.7%) compared to CR-TKA (18.0%).
Conclusion: Joint awareness of the BCR-TKA was not significantly reduced compared to the CR-TKA. However, this study illustrates that bi-cruciate-retaining surgical technique for TKA is a promising step further in the pursuit of reducing joint awareness and retrieving the artificial forgotten total knee. Since a functional ACL increases rotational stability and proprioception, future research should focus on knee kinematics in modern BCR-TKA measured with gait analyses.
Level of evidence: IV therapeutic, retrospective, cohort study.
Keywords: 12-item Forgotten Joint Score; Bi-cruciate-retaining knee arthroplasty; Cruciate-retaining knee arthroplasty; Osteoarthritis; Patient-reported outcome measurements; Patients-specific instrumentation; Total knee replacement.