Three-year clinical and radiological results of a cruciate-retaining type of the knee prosthesis with anatomical geometry developed in Japan

Abstract

Background: The FINE total knee was developed in Japan and clinical use began in 2001. It has unique design features, including an oblique 3^o femorotibial joint line that reproduces anatomical geometry. Although 20 years have passed since the FINE knee was clinically used for the first time in Japan, a formal clinical evaluation including patient-reported and radiographic outcomes has not been undertaken.

Methods: A total of 175 consecutive primary cruciate-retaining (CR)-FINE total knee arthroplasties (TKAs) at our hospital between February 2015 and March 2017 were included in this study. Three years postoperatively, range of motion (ROM), Knee Society Score (KSS), Knee Injury and Osteoarthritis Outcome Score (KOOS) and Forgotten Joint Score (FJS) were recorded and compared with preoperative scores. Radiographic analyses including mechanical alignment, component alignment, and incidence of radiolucent lines also were undertaken based on the radiographs 3 years postoperatively.

Results: One-hundred twenty-two knees (70%) were available for 3-year follow-up data using KOOS, except for the sports subscale. Postoperative KOOS-symptom, -pain and -ADL were > 85 points, but KOOS-sports, -QOL and FJS were less satisfactory. ROM, KSS and all the subscales of KOOS were significantly improved compared with preoperative scores. Postoperative mean FJS was 66 and was significantly correlated with all the subscales of KOOS, but not with postoperative ROM. Radiolucent lines ≧1 mm wide were detected in five knees (4.1%). There were no major complications needing revision surgeries.

Conclusions: Patient-reported outcomes (PROs) for symptoms, pain and ADL after the CR-FINE TKA were generally improved, but those for sports, QOL and FJS were improved less. The incidence of radiolucent lines was rare but detected around the femoral components. With the mid- to long-term follow-up, improvements of surgical technique will be necessary to achieve better PROs from patients receiving the FINE knee.

Keywords: Cruciate-retaining (CR); FINE total knee; Patient-reported outcomes (PROs); Total knee arthroplasty (TKA).

Fig. 1

The FINE total knee. The femoral condyle has an asymmetric shape and femorotibial joint line with an oblique 3^o both in coronal (left) and axial (right) planes which is incorporated into the implant design. The medial surface of the polyethylene insert has a convex curve while the lateral surface possesses a flat surface. FINE reproduces anatomical geometry by conducting osteotomy perpendicular to the mechanical axis. The figure is reprinted with minor modifications from Fig. 1 in the reference no. [15]

Fig. 2

A flowchart of the patients during this study. TKA, total knee arthroplasty; KOOS, Knee Injury and Osteoarthritis Outcome Scores; FJS, Forgotten Joint Score

Fig. 3

Representative (a) anteroposterior radiograph of a CR-FINE TKA showing measurement of the distal femoral valgus angle (DFVA; α) and proximal tibia varus angle (PTVA, β). b Lateral radiograph showing measurement of the femoral flexion angle (FFA; γ) and tibial slope (TS; σ). c Full-length standing radiograph showing measurement of the hip-knee-ankle (HKA) angle. Varus mechanical alignment is designated as positive for HKA angle