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

Nakajima et al. BMC Musculoskeletal Disorders https://doi.org/10.1186/s12891-021-04114-x (2021) 22:241 RESEARCH ARTICLE Open Access Three-year clinical and radiological results of a cruciate-retaining type of the knee prosthesis with anatomical geometry developed in Japan Arata Nakajima1*, Manabu Yamada1, Masato Sonobe1, Yorikazu Akatsu1, Masahiko Saito2, Keiichiro Yamamoto1, Junya Saito1, Masaki Norimoto1, Keita Koyama1, Hiroshi Takahashi3, Yasuchika Aoki4,5, Toru Suguro6 and Koichi Nakagawa1 Abstract Background: The FINE total knee was developed in Japan and clinical use began in 2001. It has unique design features, including an oblique 3o 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: FINE total knee, Cruciate-retaining (CR), Total knee arthroplasty (TKA), Patient-reported outcomes (PROs) * Correspondence: 1 Department of Orthopaedic Surgery, Toho University Sakura Medical Center, 564-1 Shimoshizu, Sakura, Chiba 285-8741, Japan Full list of author information is available at the end of the article © The Author(s). 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Nakajima et al. BMC Musculoskeletal Disorders (2021) 22:241 Background Although the outcomes of total knee arthroplasty (TKA) are generally acceptable, approximately 20% of patients have some complaints after TKA [1–3]. The reasons for dissatisfaction after TKA remain poorly understood; however, failure of restoration of a physiological joint line has been suggested as a causative factor. In 2011, Bellemans introduced kinematically aligned (KA)-TKA as a surgical technique to realize a physiological joint line [4]. The goal of KA-TKA is to maintain the orientation of the native joint line. While there have been studies showing that KA-TKA provides equivalent or better function and similar survival rate to mechanically aligned (MA)-TKA [5–10], the longevity of polyethylene inserts and femoral and/or tibial components implanted not perpendicular to the mechanical axis are a concern [11–13]. However, as a concise follow-up at 20 years of modern TKA with cement reported that neutral mechanical alignment did not provide better implant survivorship than the outlier group [14], it remains unknown whether KA-TKA provides better clinical outcomes and survivorship than MA-TKA. The FINE total knee has been developed in Japan and used for approximately 20,000 TKAs of Japanese patients since 2001. It has unique design features, including an oblique 3o femorotibial joint line (Fig. 1). This feature allows to reproduce anatomical geometry by Page 2 of 9 cutting the bone perpendicular to the mechanical axis. The sagittal curvature of the femoral component has dual-radii in extension and flexion range. The polyethylene insert also has a unique design; the medial surface has a convex curve with increased conformity to the femoral component while the lateral has a flat surface. These features of the FINE knee allow KA-TKA via conventional osteotomy, and enhance internal rotation of the tibia and femoral rollback via medial pivot motion [15], which would expect better patient-reported outcomes. Although 20 years have passed since this implant was clinically used for the first time in Japan, a formal clinical evaluation including patient-reported and radiographic outcomes has not been undertaken. The aim of the present study was to evaluate the 3-year clinical results including patient-reported and radiographic outcomes in Japanese patients receiving a cruciate-retaining (CR) type of the FINE total knee. Methods Patients A total of 175 consecutive primary TKAs using a CR type of the FINE total knee (Teijin-Nakashima Medical Co. Ltd., Okayama, Japan) in 157 patients at our hospital between February 2015 and March 2017 were included in this study. One patient (one TKA) died from TKA- Fig. 1 The FINE total knee. The femoral condyle has an asymmetric shape and femorotibial joint line with an oblique 3o 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 (...truncated)