The concept of the recently reintroduced bi-cruciate retaining design in knee arthroplasty is to allow a more physiological movement of the knee, a better proprioception and to mimic a closer to the normal knee function. The purpose of the present study was to evaluate and compare the clinical outcomes of two groups of patients subject to bi-cruciate retaining (BCR) or posterior-stabilized (PS) implants. It was hypothesized that patients treated with BCR prosthesis will present higher satisfaction and better clinical and functional results compared to those treated by PS implants.
This prospective controlled trial included twenty-five patients who were treated for primary knee osteoarthritis and who were assigned in two equal groups. Those with functioning cruciate ligaments received bi-cruciate retaining prosthesis. In case of ligaments' insufficiency, the posterior-stabilised design was selected. Primary outcome was knee flexion and functional results as recorded by the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. Secondary outcomes included the visual analogue scale (VAS) for pain, treatment related complications and surgical time.
Complete data were recorded for all patients with a minimum of 2 years follow-up. The study populations were matched for their demographic characteristics and their co-morbidities. This study found a statistically significant improvement in all the analysed clinical and functional assessment tools from baseline to the latest follow-up (p<0.05) for both groups. However, no statistically significant difference was found between the two groups. The mean postoperative flexion was 121 and 120 degrees for the BCR and the PS groups respectively. At final follow-up the BCR group had slightly higher mean KOOS in three sub-scales (symptoms, activities of daily living and quality of life). Secondary outcomes were similar in both groups. Hence, complications were higher in BCR group.
There was no evidence of clinical superiority of bi-cruciate retaining compared to posterior stabilized knee implants. Furthermore, it seems to be associated with a higher number of revision surgeries and prolonged surgical time. Therefore, further randomized studies with a higher number of participants and a longer follow-up on comparison of bi-cruciate retaining and posterior stabilized implants in primary knee osteoarthritis could be rewarding.