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Iida T.,Osaka City University | Minoda Y.,Osaka City University | Kadoya Y.,Hanwa Joint Reconstruction Center | Matsui Y.,Saiseikai Nakatsu Hospital | And 4 more authors.
Knee Surgery, Sports Traumatology, Arthroscopy | Year: 2012

Purpose: The medial pivot total knee prosthesis has been designed to reproduce physiological knee kinematics. It has been reported that alumina ceramic femoral components reduce polyethylene wear. Thus, medial pivot total knee prostheses with alumina ceramic femoral components were introduced. The purpose of this study was to evaluate the clinical results of patients who underwent newly introduced alumina medial pivot total knee arthroplasties (TKA). Methods: We evaluated the clinical results of 107 alumina medial pivot TKAs in 80 consecutive patients with a mean follow-up period of 5 years. Results: Alumina medial pivot TKAs provided significant improvements in the patients' Knee Society knee scores, function scores and post-operative ranges of motion compared with their pre-operative statuses (each, P < 0. 05). There was no statistical correlation between the change in maximum knee flexion and the increase in posterior condylar offset. Revision surgery was required in one knee due to a post-operative fracture of the tibial plateau after a fall that occurred 2 years postoperatively. No knees had aseptic loosening, osteolysis, or ceramic fractures. The survival rate was 98. 6% at 5 years. Conclusions: This study demonstrates satisfactory mid-term clinical results for patients receiving the alumina medial pivot prosthesis. Level of evidence: Therapeutic study, Level IV. © 2011 Springer-Verlag.


Minoda Y.,Osaka City University | Nakagawa S.,Osaka Rosai Hospital | Sugama R.,Osaka General Hospital | Ikawa T.,Hanwa Joint Reconstruction Center | And 4 more authors.
Knee Surgery, Sports Traumatology, Arthroscopy | Year: 2014

Purpose: It was hypothesised that implantation of a total knee prosthesis may change the size and shape of the joint gap. To test this hypothesis, a tensor device was used which was specifically designed to reproduce the conditions before and after implantation, including attachment of the polyethylene insert trial. This study aimed to compare the joint gaps before and after implantation of a total knee prosthesis using this new tensor device.Methods: A total of 259 primary varus knees were included in this study. Knees were exposed using a medial parapatellar approach, and the anterior and posterior cruciate ligaments were resected. After the trial reduction, the intraoperative joint gap kinematics was measured using the tensor device.Results: Implantation of a total knee prosthesis decreased the size of the extension joint gap and made it valgus, but did not influence the size or shape of the flexion joint gap.Conclusions: The present findings suggest that the classical gap technique, which creates equal and rectangular extension and flexion joint gaps in the bone cutting surface, results in an imbalance between the extension and flexion joint gaps after implantation. To achieve equal and rectangular extension and flexion joint gaps after implantation, the prepared extension joint gap should be about 2 mm larger than the flexion joint gap and slightly varus before implantation in primary varus knees.Level of evidence: Therapeutic study, Level II. © 2014 European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA)


Minoda Y.,Osaka City University | Nakagawa S.,Osaka Rosai Hospital | Sugama R.,Osaka General Hospital | Ikawa T.,Hanwa Joint Reconstruction Center | And 3 more authors.
Knee | Year: 2014

Background: Soft-tissue balancing of the knee is fundamental to the success of a total knee arthroplasty (TKA). In posterior-stabilized TKA, there is no stabilizer of the anterior-posterior translation in the midflexion range in which the cam-post mechanism does not engage yet. Therefore, instability in the midflexion range is suspected to occur in posterior-stabilized TKA. The purpose of this study was to measure the joint gap throughout a full range of motion and to analyze the joint gap laxity in the midflexion range after implantation of a mobile-bearing posterior-stabilized total knee prosthesis. Methods: Joint gap kinematics in 259 knees with varus osteoarthritis were measured during TKAs using a tensor device with the same shape of a total knee prosthesis of the same design was used. After the implantation of a mobile-bearing posterior-stabilized prosthesis and the reduction of the patellofemoral joint, the joint gap was measured at 0°, 30°, 60°, 90°, 120°, and 145° of flexion. Results: The center size of the joint gap was tight in extension and deep flexion and loose at midflexion ranges, especially at 30° of flexion (p<. 0.001). The symmetry of the joint gap was varus at 0° and 145° of flexion (p<. 0.001). Conclusions: Our results showed the joint gap laxity in the midflexion range after the implantation of a mobile-bearing posterior-stabilized prosthesis. Our new tensor device, which can attach the polyethylene insert trial, will provide the important information about the joint gap kinematics after implantation of total knee prostheses. Level of evidence: IV. © 2014 Elsevier B.V.


Minoda Y.,Osaka City University | Nakagawa S.,Osaka Rosai Hospital | Sugama R.,Osaka General Hospital | Ikawa T.,Hanwa Joint Reconstruction Center | And 2 more authors.
Journal of Arthroplasty | Year: 2015

The relationship between the joint gap before and after implantation in 259 knees during the total knee arthroplasty was investigated using a tensor device which can attach the polyethylene insert trial. Patients were divided into following 3 groups according to the joint gap balance before implantation (flexion joint gap. - extension joint gap); group 1: >. 1. mm; group 2: -. 1 to 1. mm, and group 3: <-1. mm. Joint gap after implantation was loose at 30°, 60°, 90°, and 120° of flexion in group 1 and 2, but loose only at 30° of flexion in group 3 (p. <. 0.01). This study showed that loose flexion joint gap before implantation increased the risk of joint gap laxity after implantation especially at midflexion ranges. © 2014 Elsevier Inc..


PubMed | Oita University, Osaka Rosai Hospital, Osaka General Hospital, Osaka City University and 2 more.
Type: Journal Article | Journal: Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA | Year: 2014

It was hypothesised that implantation of a total knee prosthesis may change the size and shape of the joint gap. To test this hypothesis, a tensor device was used which was specifically designed to reproduce the conditions before and after implantation, including attachment of the polyethylene insert trial. This study aimed to compare the joint gaps before and after implantation of a total knee prosthesis using this new tensor device.A total of 259 primary varus knees were included in this study. Knees were exposed using a medial parapatellar approach, and the anterior and posterior cruciate ligaments were resected. After the trial reduction, the intraoperative joint gap kinematics was measured using the tensor device.Implantation of a total knee prosthesis decreased the size of the extension joint gap and made it valgus, but did not influence the size or shape of the flexion joint gap.The present findings suggest that the classical gap technique, which creates equal and rectangular extension and flexion joint gaps in the bone cutting surface, results in an imbalance between the extension and flexion joint gaps after implantation. To achieve equal and rectangular extension and flexion joint gaps after implantation, the prepared extension joint gap should be about 2mm larger than the flexion joint gap and slightly varus before implantation in primary varus knees.Therapeutic study, Level II.

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