Short-term clinical results of bicruciate-retaining total knee arthroplasty using functional alignment

Background: Bicruciate-retaining (BCR) prosthesis has been introduced to recreate normal knee movement by preserving both the anterior and posterior cruciate ligaments. However, the use of BCR total knee arthroplasty (TKA) is still debatable because of several disappointing reports. We have been performing BCR TKAs with functional alignment (FA). This study aimed to reveal the limb alignment and soft tissue balance of FA-BCR TKAs and compare the clinical outcomes of FA-BCR TKAs with those of unicompartmental knee arthroplasty (UKA). Methods This study evaluated the joint component gap of BCR TKA intraoperatively and measured the postoperative hip–knee–ankle (HKA) angle, medial proximal tibial angle (MPTA), and lateral distal femoral angle (LDFA) using full-length standing radiography. The short-term clinical outcomes of BCR TKAs were compared with those of UKA at an average of 2 years postoperatively (1-4yeras). Results The coronal alignment values of FA-BCR TKA were as follows: HKA angle, 177.9° ± 2.3°; MTPA, 85.4° ± 1.9°; and LDFA, 87.5° ± 1.9°. The joint component gaps at flexion angles of 10°, 30°, 60°, and 90° were 11.1 ± 1.2, 10.9 ± 1.4, 10.7 ± 1.3, and 11.2 ± 1.4 mm for the medial compartment and 12.9 ± 1.5, 12.6 ± 1.8, 12.5 ± 1.8 and 12.5 ± 1.7 mm for the lateral compartment, respectively. The patient expectation score and maximum extension angle of FA-BCR TKA were significantly better than those of UKAs. Conclusions The short-term clinical outcomes of FA-BCR TKA were comparable or a slightly superior to those of UKAs.